This invention relates generally to the field of implantable medical devices, and more particularly to implantable heart monitors and therapy delivery devices.
A wide variety of implantable heart monitors and therapy delivery devices have been developed including pacemakers, cardioverter/defibrillators, heart pumps, cardiomyostimulators, ischemia treatment devices, and drug delivery devices. Most of these cardiac systems include electrodes for sensing and sense amplifiers for recording and/or deriving sense event signals.
These devices typically utilize the sense event signals to detect problems with a patient""s cardiac system and to delivery of the therapy. Prior art disclosures have been made suggesting methods for detecting cardiac conditions including:
All patents listed in Table 1 above are hereby incorporated by reference herein in their respective entireties. As those of ordinary skill in the art will appreciate readily upon reading the Summary of the Invention, Detailed Description and Claims set forth below, many of the devices and methods disclosed in the patents of Table 1 may be modified advantageously by using the teachings of the present invention.
The invention has certain objects and, in general, provides solutions to problems existing in the prior art in detecting the onset of a cardiac condition. One of the most dangerous cardiac conditions is a myocardial infarction in which a section of heart muscle dies due to a loss of blood flow from a coronary artery. Most myocardial infarctions occur in the left ventricle and cause sharp pain in the chest, which can spread to the arms and throat. In addition, the invention provides techniques for detecting other cardiac conditions such as an occlusion of a coronary artery by a thrombus or ischemic heart disease. Unlike other known techniques, cardiac conditions are detected, according to the invention, by monitoring the flow of blood as it exits the coronary system through the coronary sinus. In addition, electrical activity in the heart is sensed for any irregularities, such as an elevated ST segment of the heartbeat.
The features of the invention may be incorporated in a variety of embodiments. For example, in one embodiment a system includes a lead for implantation in the coronary sinus of a patient""s heart. The lead includes a sensor for measuring the velocity of blood flowing through the coronary sinus. An implantable medical device (IMD) coupled to the lead monitors a blood flow signal from the sensor as well as electrical activity within the heart. The implantable medical device system includes a microprocessor circuit to analyze the blood flow signal and the electrical activity signal in order to detect cardiac conditions.
According to one feature of the invention, the IMD delivers an alarm to the patient or begins delivering drug therapy, preferably delivery of rapid action thrombolytics, as a function of sensed electrical activity and the blood flow through the coronary sinus. For example, the IMD can include an audible alarm, a muscle stimulating alarm or both. In addition, the IMD can include a drug delivery pump for dispensing therapeutic drugs or a catheter to deliver prophylactic arrhythmia therapy. The system can be constructed to vary the treatment, and notably the dosage, according to the sensed elevation of the ST segment and the blood flow.
Various embodiments of the invention are set forth in the accompanying drawings and the description below. Other features and advantages of the invention will become apparent from the description, the drawings, and the claims.